diff --git a/src/librustc_codegen_ssa/mir/mod.rs b/src/librustc_codegen_ssa/mir/mod.rs
index 870b97401f47a..a90dc356c92e8 100644
--- a/src/librustc_codegen_ssa/mir/mod.rs
+++ b/src/librustc_codegen_ssa/mir/mod.rs
@@ -679,6 +679,7 @@ fn arg_local_refs<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
                         .zip(state_tys)
                         .enumerate()
                         .filter_map(move |(i, (decl, ty))| {
+                            let ty = fx.monomorphize(&ty);
                             decl.name.map(|name| (i + upvar_count + 1, name, false, ty))
                         })
                 }).into_iter().flatten();
diff --git a/src/test/run-pass/generator/issue-58888.rs b/src/test/run-pass/generator/issue-58888.rs
new file mode 100644
index 0000000000000..43b37a9afc2cc
--- /dev/null
+++ b/src/test/run-pass/generator/issue-58888.rs
@@ -0,0 +1,27 @@
+// run-pass
+// compile-flags: -g
+
+#![feature(generators, generator_trait)]
+
+use std::ops::Generator;
+
+struct Database;
+
+impl Database {
+    fn get_connection(&self) -> impl Iterator<Item = ()> {
+        Some(()).into_iter()
+    }
+
+    fn check_connection(&self) -> impl Generator<Yield = (), Return = ()> + '_ {
+        move || {
+            let iter = self.get_connection();
+            for i in iter {
+                yield i
+            }
+        }
+    }
+}
+
+fn main() {
+    Database.check_connection();
+}